The present invention relates to fracturing of subterranean formations, such as in a well, by hydrojetting fluid from a jetting tool, and more particularly, to methods and apparatus for creating multiple fractures in a formation using such tools at substantially the same time.
Hydraulic fracturing is often utilized to stimulate the production of hydrocarbons from subterranean formations penetrated by wellbores. In performing hydraulic fracturing treatments, a portion of a formation to be fractured is isolated using convention packers or the like, and a fracturing fluid is pumped through the wellbore into the isolated portion of the formation to be stimulated at a rate and pressure such that fractures are formed and extended in the formation. Propping agents function to prevent the fractures from closing and thereby provide conductive channels in the formation through which produced fluids can readily flow to the wellbore.
In wells penetrating very low to medium permeability formations, and wells not producing to expectations, it is often desirable to create fractures in the formations near the wellbores in order to improve hydrocarbon production from the formations. In order to create such fractures in formations penetrated by cased or open hole wellbores conventionally, a sealing mechanism such as one or more packers must be utilized to isolate the portion of the subterranean formation to be fractured. When used in open hole wellbores, such sealing mechanisms are not as effective, as fractures tend to create open passages past the sealing mechanism. In cased wells, sealing mechanisms are effective; but their use and installation are time consuming and add considerable expense to the fracturing treatment.
As a solution to this problem, a unique stimulation technique was formulated. This technique does not require sealing mechanisms; instead, sealing is performed dynamically. That is, sealing is achieved using velocity of the fluid. This method was disclosed in U.S. Pat. No. 5,765,642. Using this method, fractures are created one at a time. However, sometimes there are situations where a few fractures must be created at the same time. In U.S. Pat. No. 5,765,642, the jet nozzles are placed such that they are located on the same plane while jet direction is also on the same plane. Therefore, placing jet nozzles on multiple parallel planes would be desirable for simultaneous placement of such multiple fractures. Note that, if the parallel planes are too close to each other, it will cause a single fracture to occur.
Thus, there is a need for improved methods of treating formations to improve hydrocarbon production therefrom which are relatively simple and inexpensive to perform.